Waving U.S. and Mexican flags, the protesters confronted police in the city, which sits just 24 kilometers from the Mexican border and where a third of residents are Latino.

Police said they made three arrests, including that of one man who climbed a railing separating protesters from officers. His arrest led protesters to spray water and throw empty plastic bottles at police.

Police officers take a woman into custody after a campaign rally for Republican presidential candidate Donald Trump in Fresno, Calif., May 27, 2016.

Earlier Friday, a smaller group of demonstrators was on hand as Trump told supporters in the central California city of Fresno that he could solve their water crisis, declaring, "There is no drought.''

Trump accused state officials of denying water to Central Valley farmers so they can send it out to sea "to protect a certain kind of 3-inch fish.''

The 3-inch Delta smelt is a native California fish on the brink of extinction. The smelt has become an emblem in the state's battles over environmental laws and water distribution.

Fresno is in the heart of the state's rich agricultural area. The state's five-year drought is raising the stakes in water disputes among farmers, cities and environmental interests. California last year capped the driest four-year period in its history, with record-low rainfall and snow.

“If I win, believe me, we’re going to start opening up the water so that you can have your farmers survive, so that your job market will get better,” Trump told cheering supporters.

A count by The Associated Press found Thursday that Trump has reached the required number of delegates to officially clinch the Republican nomination.